If every company is using AI now, how to set your startup apart?

Same as before AI - by solving a problem. AI is a tool, not a goal. If it can solve a problem, great... build a solution with it. If not, build a solution without it. But focus on what you are solving, not what flavor of hammer you are using to pound that nail.

For starters, don't shout at the market that AI is your differentiator. Lead by value, not by adoption of technology.