ACT scores and interpretation... please?

Your scores are not bad, but you are not going to get into any big schools with a 21. That is what my daughter had also and she went to a small private school which worked out perfect for her. I would recommend that you retake the test to try to get a better score even if it is only a point or two. I am going from experience with my two children not from sources. Whatever schools you are looking at, check their ACT score averages. Some schools have cut-off scores. Good luck!