Response to @tracynerdgirl: "can we attempt the math as to why Captain America didn't age while under ice but he stays in the past all of a sudden he ages?"
"Oh, we can certainly attempt the math on that. Steve Rogers was born in 1918, and he crashed into the Arctic in March of 1945, after which he spent 67 years cryogenically preserved at extremely low temperatures that prevented the enzymatic activity that causes aging. He was revied in 2012 and helped to defeat Thanos in 2023, at which point he was chronologically 105 years old, 38 years of which he had spent unfrozen. He then traveled back to 1949 to reunite with Peggy and lived out another 74 years before eventually returning to New York as an old man to pass the shield on to Sam. At that point, Steve had been unfrozen for 112 years, and was chronologically a total of 179 years old. For comparison, James Howlett was 197 years old when he died at the end of Logan, and he had a genetic healing factor."