Affiliate Marketing Secrets

I’ve done a lot of digging on different theories that explain reality, with string theory (and all of its affiliates) appearing to be the most merited explanation. Searching for answers always leads to more questions, of course.
M-theory and the 11 dimensions that supposedly exist (assuming this is the correct theory) holds that there are limitless universes parallel to ours that hold that every possible outcome to anything will happen in these unlimited “bubbles” of universes. This seems a little bit iffy in light of the following question I will ask.
What I wanted to ask is; life is created in a way to perceive what best suits its own survival and nothing more. Therefor, is it not highly likely that there are no means to perceive any of these dimensions because the tiny niche of existence we occupy will simply not permit it? If there are particles that exist right in front of us that do not have the capacity to interact with the forms of matter that we can interact with, then is there simply no way of observing them?
I want to know A) What evidence points to the existence of the theoretical particles (Higs bosons/field, tachyons, etc) B) what makes these theoretical particles necessary in order for the math to work, and C) How much matter/particles/inter dimensional debris/etc is hypothesized to be undiscovered or completely undiscoverable?