You absolutely need those basic skills to be in a position to produce anything on Unreal Engine but its the sheer amount of work that comes after to produce anything of value is where the challenge is in my opinion. It almost certainly involves a dedicated asset generation capacity to generate enough novelty and/or a polished, smooth mechanic that can handle all the edge cases thrown at it. And there's a reason why the UE tools out of the box are so limited and frustrating to use to the point that its impossible to work on anything without opening up your wallet to purchase productivity tools sold on its marketplace and still struggle with the workload. Especially when it requires you to become proficient at C++ because blueprint's value drops outside animation rigging and VFX, both of which Unity's 3rd party marketplace tools have filled rendering UE's initial user friendliness nil. You are stuck with an enterprise tool marketed and suited for large studios but you thought you could make indie games faster than Unity.