1. We don't know if the universe follows any rules precisely. We can never know because the only way to know that a rule is being followed unconditionally would be to exhaustively verify every event in the universe to see if it follows that rule, which is impossible.

2. There's not just one mental process. There are an infinite number (most likely) of mental processes. But even though we're not both part of the same mental process, we're both part of the same causal process. The reason we perceive ourselves as discrete entities is: 1. mental processes (thoughts) can be both true and false, 2. true thoughts are more rare than false thoughts, 3. false thoughts are still capable of doing work, and therefore, our survival has relied on the false thought that each of us is a separate individual, even though the truth is that we're causally dependent on one another, our environment, etc.

"we intuitively believe that we are different, disconnected entities"

my take is that we intuitively know we are one, not disconnected. but the short site, not listening to that intuition, is seeing only duality.

the universe is a projection of the sum of all thoughts it is not better because we all as a sum do not create it better :)

I blame subconscious denial. Seriously.