The new construction, builders and development advocates say, is both the product of — and is helping to spearhead — Manayunk's second rebirth. (Its first came in the late 1980s.) For the first time, they say, the introduction of pricier, amenity-heavy apartments — such as Realen Properties' the Isle and O'Neill Properties' Royal Athena just across the bridge — are attracting well-to-do older millennials and empty nesters to the Manayunk area, decades after such groups abandoned it amid a deluge of college students in the early 2000s.