Would I be good for artistic gymnastics?

Kitty82 is pretty much right. At age 16 with , you're likely too late to become elite in gymnastics or cheerleader. Elite gymnasts typically start training at age 4 or 5 and if they are exceptionally talented make it to elite around age 15-17. These aren't Olympic caliber gymnasts, but more of the ones that will compete in college. So you can see where just starting at age 16 doesn't leave you much time to become proficient at it. You would be doing it for fun and recreation, you're probably not going to be doing it at competitive levels. In gymnastics you don't start competing until level 4, which would take most people 2-3 years to get to. You don't get to chose your own choreography until level 7, which you likely will not reach. I'm not trying to be mean, I'm just being realistic.

Cheerleading isn't quite as demanding but, again you really should've started about 5 or 6 years ago if you wanted to do competition cheer.

As a new starter at 16 your build isn't really going to be that important to your progress in artistic gymnastics (unless you were obese which doesn't apply.) There are a lot of factors that contribute to success, natural talent, balance, coordination, strength, flexibility, ability to take direction, work rate, dedication and yes, build. But build and height are about the least important out of all that. They matter at high level because everything matters at high level. For you though it just isn't going to be important.

Artistic takes more strength than rhythmic and a lot more power. (This does inhibit flexibility for dance which is why career ballet dancers won't do gymnastics but again this becomes more of an issue the more training and higher level you are in either activity and is not a problem for a beginner or someone doing gym and dance for a fun hobby.) Those are both things that you can develop to a good extent through conditioning. Similarly rhythmic requires good static strength and great flexibility and coordination which you can train and improve. One or the other might come more naturally to you but you could improve at either.

So you could certainly do artistic gymnastics and improve at it and learn new skills. Starting at your age you won't be competitive in either artistic or rhythmic so you really just should pick whichever you think you would most enjoy. If you are going to keep up dancing you might want to artistic for more of a contrast. If this is instead of dance you might want to do rhythmic because it is dance based. If you want to do a sport where you work in a team you might prefer cheer, team gym or acro (though there are group routines in rhythmic too.) A lot of sports classes will let you do your first session without commitment as a taster (sometimes free or sometimes a pro-rata fee.) It would probably be a good idea for you to take advantage of that to get a better feel for what the classes are like and help you decide what you would most enjoy.