SANTA CLARA >> Christian McCaffrey emerged “sore but felt good” from Sunday’s season debut featuring 56 snaps, 19 touches and 107 yards from scrimmage. The 49ers’ 23-20 win over the Buccaneers in Tampa launched his comeback after two-plus months battling Achilles tendinitis.

“When you’re dealing with an injury and come back, it’s a common misconception you have fresh legs,” McCaffrey said Thursday. “For a long time there I was struggling walking to the bathroom. So you can’t train for a long time. They’re fresh in the sense they haven’t been beat up, but you also have to get back into training. That’s why it takes long sometimes.”

While he rehabbed with the 49ers’ strength staff and sought advice from other athletes with similar ailments, McCaffrey was aghast at how outsiders portrayed themselves as experts in his plight.

“One thing I learned about the whole process is you get a lot of Instagram doctors out there,” McCaffrey said. “I had guys diagnosing my injury, PhD doctors.

“I’m watching a Sunday night game and some doctor is talking about my injury on TV. I couldn’t believe it. I’d never talked to him in my life, he’d never seen imaging, talked to me, diagnosed me. It’s just kind of the world we live in now.”

McCaffrey resumed practicing last week after 51 days away from team activities, and he came off the injured reserve list Saturday.

“I tried to stay focused on my plan, what I trusted in, go from there and limit the outside noise,” he said. “Because everyone has an answer and they’re all different.”

McCaffrey approved of his debut outing, especially his on-field vision as well as what he saw on film afterward, including a 30-yard reception from a pressured Brock Purdy on a fourth-quarter touchdown drive.

“It was insane,” McCaffrey said of the throw. “Most of the time when you’re throwing that ball and you see it go that high, that ball is going to go much farther than 20 yards. But he somehow managed to drop it in a bucket on his back foot with pressure in his face.”

McCaffrey’s encore comes Sunday when the ascending 49ers (5-4) host the spiraling Seahawks (4-5).

“They say ‘Any Given Sunday’ for a reason. This is a division game, at home, with a good team,” McCaffrey added. “We know what this game is about: going out there and executing and playing as hard as humanly possible.”

Achilles tendinitis, however, remains a mystifying ailment to last season’s AP NFL Offensive Player of the Year. He missed most of training camp, then returned to practice for two weeks before the season opener in which he was a game-time scratch.

“I wish I had the answer of ‘Here is exactly what to do before and after,’ ” McCaffrey said. “Sometimes maybe I overcomplicated things. Who knows, man? I mean, I’m learning on the fly just like everybody else. Sometimes things work, sometimes they don’t.

“Unfortunately the first part of the season, they didn’t work for me, and it’s just something I’ll have to live with,” McCaffrey said. “But I feel good now, I like the plan now, and I’ll keep rolling.”

Kittle returns >> Tight end George Kittle (hamstring) returned to practice after missing Wednesday’s session, but remaining out were left tackle Trent Williams (ankle, wrist), defensive end Nick Bosa (hip), punter Mitch Wishnowsky (back), cornerback Charvarius Ward (bereavement leave) and defensive tackle Kevin Givens (groin).

Wide receiver Jauan Jennings (ankle) was added to the injury report after being limited, as were wide receiver Chris Conley (hamstring) and guard Jon Feliciano (knee). Running back Jordan Mason (shoulder; non-contact jersey) was not on the injury report.

LOCKING UP LENOIR >> Defensive coordinator Nick Sorensen said he is ecstatic the 49ers locked up Deommodore Lenoir to a five-year extension Wednesday, noting how Lenoir’s blossomed not only as an outside cornerback but one who excels inside against slot receivers when needed.

“(With) his play style and his versatility, he’s selfless. He’s a pure football player,” Sorensen said. “The old thought is guys who play nickel won’t get paid. It’s hard to do both. There’s more value than people realize, and people that know football know that’s hard to do.”