“…at least asked my teachers to revise it a few more times”
Umm, no. You revise your own work.
You should know enough about a tippy top “dream” to ask yourself, “They would want me because…” What do you think makes you especially competitive?
And even with a Why Us or Why this Major, the idea is to “show, not just tell.” They want to find the traits they value. Not just an explanation. (Nor mostly about middle school.)
One main focus can actually be risky, when they look for broad(er) curiosity, wider application of your skills and experiences.
Review your apps for other colleges, see what your match might be, be sure it shows. Be willing to tweak. Or find your own best matches and safeties.