Jimmy Garoppolo needs to play.

Just ask Kyle Shanahan.

The 49ers’ head coach hammered home that message Monday night when asked about his quarterback’s ugly performance in a preseason win at Denver, Garoppolo’s first game since he tore his ACL in September.

“It’s just about getting him out there and playing again.”

“The more he can play, the better.”

“We just want to get him out there and get some reps and play some football.”

“It’s about him playing and getting reps with our team.”

“It’s about getting him reps and putting him in different situations and letting him play as much as possible.”

The solution seems simple, but the problem is obvious: Garoppolo probably won’t play much more than two quarters before he plays in a game that matters.

That is, Garoppolo figures to play at least the first half in Saturday’s preseason game at Kansas City before sitting out next week’s exhibition finale.

So will he be ready for the season opener at Tampa Bay on Sept. 8? Even the most optimistic of the Faithful might be struggling with that answer after watching Garoppolo complete 1 of 6 passes for zero yards and throw an interception against the Broncos, who also dropped what should have been an easy interception.

Along with last season’s inactivity because of his injury, Shanahan has pointed to Garoppolo’s inexperience as a factor when stressing the need for him to play. Garoppolo has made just 10 career starts.

However, he has proven he can flourish with far less experience. In 2017, when he’d made two career starts, Garoppolo became the 49ers’ starter a month after he’d been traded and went 5-0 with a previously 1-10 team despite having a loose grasp of the playbook.

Two years later, Garoppolo is more experienced, but is returning from a serious injury.

The 49ers have noted his recovery has been excellent. In fact, general manager John Lynch termed it “flawless” on Saturday. On Monday, Shanahan said Garoppolo has “been healthy since OTAs. We’re not worried about the knee right now.”

However, Garoppolo wasn’t quite as definitive when asked if he thought about his knee during Monday’s game.

“Honestly, I really wasn’t thinking about it out there, so I’m happy about that,” Garoppolo said. “Just in general, it didn’t bother me that much.”

Many athletes have detailed the mental hurdles involved with returning from an injury. On Monday, minutes after Garoppolo spoke to reporters, running back Raheem Mostert said he had “a little bit of hesitation” in the preseason opener, which was his first game since he broke his forearm in November.

On Monday, Garoppolo, who was often under pressure, didn’t forcefully step into his throws on his left plant leg, the same leg where a brace covers his surgically repaired knee.

On his interception, Garoppolo was under pressure from outside linebacker Bradley Chubb and his pass, intended for running back Breida, was badly underthrown and intercepted by cornerback Isaac Yiadom, who was covering wide receiver Marquise Goodwin.

On Monday, Shanahan said Garoppolo’s throw was off target because he got hit in mid-throw, but he amended that after reviewing the game.

“I thought Jimmy got hit as he was throwing it. He didn’t,” Shanahan said. “He got rid of it too early to avoid the hit and the route hadn’t developed yet, so it didn’t go far enough down the field.”

The interception was similar to the only pick Garoppolo threw last week during two joint practices with the Broncos. On Friday, as outside linebacker Von Miller was rolling on the ground near his legs, Garoppolo floated an underthrown pass off his back foot that easily was intercepted by safety Justin Simmons.

Garoppolo was asked Monday if he’s thought about what it will be like to take his first big hit.

“Not really,” Garoppolo said. “I think those will just come naturally. It’s football, you know what you sign up for and everything, So it’s not like you’re wanting that. I think I’ll build that in due time.”

Indeed, it will happen to Garoppolo eventually.

He just needs to play.

Eric Branch is a San Francisco Chronicle staff writer. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch