Short post: Purely by chance, I met an old high school classmate of mine on the bus on the weekend.
He was talking about making the competitive swimming team, but was not that experienced and lacked the skill to compete competitively. His endurance was not too good, his speed was (in his words, “ok, but not great”), and he had an imperfect technique. He wanted though to compete in a team and maybe someday swim competitively, but was too daunted to apply because of his lack of skill.
My advice is, don’t reject yourself. Let others reject you. If you don’t make the team, you don’t make the team. Yeah it is hard being rejected by other people, but in the end, you will never know how far you can go unless you try.