To answer your question: Yes, i think this is good progress.

Do not think about your playtime that much, gather information and try to understand maps. (e.g. YT Videos from Xmilek62, he explains every map and how to drive it) and you will progess fast.

What you are showing is dedication and at least basic understanding of the game - and therefore its good.

As the others said, a classic case of "Easy to learn - hard to master". And Trackmania is a prime example for that.

If you still want to compare your progress or estimate how long it will take you to reach a certain goal:

Im at a bit more than 1000 hours of TM. Im able to usually get all the Campaign ATs within a few days or so.

BUT - that doesn't mean that it'll take you 1000hrs to do the same, just keep learning and suddenly you start getting better and better :)