Not likely. Original thinking in a "side project" is almost never about the code itself, but the ideas and end product implementation. You might be able to invent things like Carmack's BSP implementation, Torvald's Content Addressable Storage, etc. but even things like that can be aided by LLMs at this point, at least in the prototyping/idea phases. AI doesn't prevent you from having good ideas or doing original thinking if that is your goal.