The dark continent. The hopeless continent. A scar on the conscience of the world. The cradle of humankind. African renaissance, Africa rising. Amazing Africa. I am an African. Scramble for Africa. Out of Africa. Ex Africa semper aliquid novi.

There have been countless attempts to define the world's second biggest and second most populous continent, often and notoriously from outside. If measuring a nation's essence is like pinning a jelly to a wall, then asserting an entire continent's character is folly. Africa's 54 countries – even this number depends on your point of view – are home to around a billion people manifesting thousands of languages and myriad ethnicities.

This most generalised and pigeonholed of all continents cries out for nuance, shade and complexity. South Africa is reputedly the beacon of hope, embarked on a judicial inquiry into its deadliest police massacre since the end of racial apartheid.

Somalia is arguably the world's most failed state, but on Monday its troops entered the last stronghold of militant Islamists to offer the best chance of peace for 20 years.

Elsewhere, Kenya, hub of economic potential, internet entrepreneurs and Olympic champions, reeled from a grenade attack on a Sunday school; Mozambique's ruling party celebrated half a century of socialism with a lavish party worthy of Jay Gatsby; and Zimbabwe's prime minister and would-be democratic saviour apologised for leaving a trail of broken hearts in his search for a wife.

It is indeed a long way from Cape Town to Cairo. In-between are hundreds of millions of people trying to earn a living, raise families and pursue happiness. More newsworthy are the dictators and democrats, dirty wars and peaceful elections, Arab springs and sub-Saharan non-springs, abundant mineral wealth and ossified poverty, rocket scientists and subsistence farmers, thriving cultural industries and dying manufacturers.

The outside world has noticed and those externally imposed narratives of Africa are shifting. Once they were dominated by conflict, despotism, disease, televised famine and hapless victimhood.

Now, the talk is of African lions, six of the world's 10 fastest-growing economies, a booming middle class, a slew of natural resource discoveries, the next frontier for investors – not aid donors. A new Africa.

Perhaps the pendulum is in danger of swinging from one extreme to another, from pathological pessimism to a Pollyannaism no less dogmatic. Businesses, the media and politicians arguably conspire in an "optimism industry" that patronises through the soft bigotry of low expectations. It is now a common trope to quote the Economist's 2000 cover "The hopeless continent" then compare it to the same magazine's "Africa rising" from 2011.

The reality is chequered, awkward, defiant of two- or three-word headlines.

Africa accounts for about 2% of world GDP. The revolutions in Tunisia, Egypt and Libya may yet prove giant leaps for democracy, but big blows to some of Africa's strongest economies.

This year, Senegal's elections produced a smooth transition of power, but neighbouring Mali suffered a coup and loss of ground to Islamist militancy. Nigeria powers on with brilliant entrepreneurs co-existing with desperate infrastructure and violent extremists seeking to impose sharia law.

To be born female or gay in most African countries is still to be faced with a lifetime of cultural and material disadvantage. Human rights are often defined by so-called traditionalists, and sometimes governments, as a western invention, a colonisation of the mind.

Rapists continue to inflict horror on an unimaginable scale.

Homophobia is often enshrined in religious conviction and colonial-era laws.

Even devout sceptics, however, would be hard pushed to deny the (often Chinese) concrete reality of new buildings and bridges, roads and railways transforming the face of the continent. Mobile phones make it possible for users to communicate with, and send money to, relatives in faraway villages with an ease that was once unthinkable. Combined with the internet, they also make it harder for tyrannies to bury their crimes.

The number of major African conflicts is down from 12 in the mid-1990s to four today. Secondary school enrolment rose by 48% from 2000 to 2008. Deaths from malaria and Aids are in decline. In eight of the past 10 years, sub-Saharan Africa's economies have outpaced east Asia's. Africa has its super-rich elite, its middle-class shopping malls, its age of leisure and obsession with the English Premier League.

But too often this growth is jobless, meaning that Africa's fast-growing young population has the makings of a demographic timebomb. Nor does economic success appear to be any guarantor of democracy or human rights. Sub-Saharan Africa's third biggest economy, oil-rich Angola, has been ruled by the same president for 33 years.

Rwanda, one person's post-genocide miracle of stable efficiency, is another's nightmare of internal repression.

One thing is certain. There is now more rambunctious, sharp-elbowed debate than there has ever been thanks to phones, email, Facebook and Twitter. The Guardian's new Africa Network, launched today, will join the debate – around contentious issues such as quality of leadership, the legacy of colonialism, identity politics that pitch women's and homosexuals' rights against a form of cultural fundamentalism. What is "Africa" anyway and should it look east, or west, or within?

The network will showcase strong, sometimes conflicting opinions from inside and outside the continent in collaboration with a dozen independent sites. Our partners include solo bloggers such as Rosebell Kagumire in Uganda; Tolu Ogunlesi in Nigeria; and Minna Salami's Ms Afropolitan. There are also collectives such as the Daily Maverick in South Africa; the women of HerZimbabwe; and the provocative Africa is a Country. Some are from established institutions such as the Royal Africa Society's African Arguments or media groups such as the Mail & Guardian's ThoughtLeader and the online magazine Think Africa Press. There's also the development blog A View from the Cave, voices from the diaspora in Africa on the Blog; and the resource site Africa Portal. Add to this mix the Guardian's own correspondents and exclusive pieces from regional experts, and we hope you will be informed, engaged, provoked, annoyed and moved.