Intelligence is indeed just one tool. But as we see, maybe one of the best tools after a critical point. So it could be expected that after a while, evolution does converge to create intelligent beings who are able to control the environment and other species and even themselves, and with it, be the most successful of them all.

Your notion of success is a human one. Evolution doesn't care. When you reproduce before you die, you're successful.

Intelligence is in no way the best tool to guarantee reproduction, there's absolutely no inevitability to it. Grass reproduces just fine without intelligence. There's species practically unchanged for hundreds of millions of years.

There is no evolutionary plan or roadmap, it's random mutations.

Basically every other species reproduces only because we allow them to and it benefits us. If we were ever existentially threatened by a competitor, we would eradicate it from existence before it even became a legitimate threat. Single-cell organisms and viruses are the only things we struggle with totally eliminating for our benefit, but we're working on it.

Trying to eradicate would change the environment and conditions and would favour species that are resistant to our eradication attempts.

I agree that there's no plan or roadmap, so maybe I was not clear in my wording. What I mean is that given infinite time, a smart species will tend to emerge, and when it does, it will be the most successful one. So evolution (by random chance) converges to higher intelligence.