OK, I read back through the other thread and have a little more of the overall picture.
Forget about the C. The C is a problem but it’s not the big issue here. You’re missing an overall understanding of what the top selective colleges are going to want out of an applicant in general, much less what specifically appeals to subsets of the selectives.
You have the test scores that show potential, where you’re falling down is the actual results piece. GPA is part of how you show actual results and your performance - results - so far hasn’t been up to the level for most of the tippy top schools. And the same is true for your ECs.
The EC list reads like one put together by someone who is trying to “check boxes” rather than explore interests, gain knowledge or make a difference. They show again that you have potential (leadership, admittance to interesting internships and projects) but no actual results. Instead of spending an hour or two a week on that assortment of things with interesting titles but no real substance, pick a few and get some results. Did you actually get a startup running? What was/were the challenges, product, results, new understanding, next goals… Did your research produce any results? Great! What were they and where was it published? You did quiz bowl and all sorts of competitions… did you win anything or gain knowledge that prompted a revelation? Results, not participation, is what makes for impressive ECs. For the ECs to be helpful, you’ll need to show that you had a stellar result, made a difference, learned something, made impactful personal growth or something similar - not just attended. Right now your list makes it appear you’re doing a lot of attending without accomplishing much, just like in school.
The issue you’ll face with your apps is that your grades will not be enough to make you competitive at the top level, nor do you have any real EC accomplishments or story (at least not that you’ve conveyed so far). AOs and Adcoms aren’t dumb and this isn’t their first rodeo - they will be able to see your app for what it is. And right now, it is representative of someone who has a lot of potential but hasn’t done top level work to get top level results either inside or outside of school.
Does that mean you’re a failure? Not even remotely. If you make no changes at all you can go to many good schools and have a great life, even though they will be schools and a life you currently feel is beneath you. But all this does mean unless you make some major changes in understanding what top colleges want, getting some actual results and a story in your ECs and improving your grades, you shouldn’t waste your time or money on apps to 90% of the schools on your list because you have no realistic chance at entry to the programs you’re looking for.
Do you have time to change this? Yes! Getting great grades is the first piece, but you really need to work on understanding what the colleges are looking for before wasting more time on the ECs and overall plan.