Your age 30 is fine. Age is always an excuse, but mostly not true.
It’s fine for single-player shooters, which are less demanding, but speaking as someone who has packed on some decades, your reaction time definitely becomes a noticeable factor over the years for competitive multiplayer games. I definitely can’t play competitive twitch shooters nearly as well as when I was 18, which is about when your reaction time is at its best.
That being said, there are shooters where twitch time is less-critical or roles or play-styles that focus less on it.
And I don’t see how someone couldn’t learn to play with a dual-stick or trackpad (or trackball, for that matter), which is what I think OP is talking about. I haven’t had any problems picking up new input methods…that just takes time. Took time to learn when I was 18, too.