It's a good assumption... for intelligence that evolved naturally from less complex life, in an environment similar to that of Earth.

But AIs are not that. Evolution cannot reason about designs and improve them conceptually, it cannot do simulations and experiments that allow it to make large jumps and reach the optimal design quickly. Hell, it's not even goal-driven. It's limited to whatever immediate next steps are accessible. Intelligence can, which is why we've effectively beaten evolution in the scope of couple centuries (with most of actual work done in the past few decades). An intelligence designed by another intelligence doesn't have a reason to inherit limitations that come from evolutionary path dependence.

For example, we don't have the ability to surgically self-modify our own cognitive functions at runtime, but we can grant that ability to an intelligence we design.

And even if it turns out we can't design an AI, but have to evolve it without really understanding how or why it works, we still retain some control over the process itself, plus the process is happening in a different substrate and environment than the one that created us. So even in this case, there's no reason to assume the resulting AI will share our trappings.