"If not LLC, than S-Corp?"

Why is S Corp your recommended alternative to "not necessarily LLC?" Your original question presents a false dichotomy. It isn't S Corp or LLC. It's broader than that.

If only the One Person is the business and is the legal entity "owner," then you might be fine with Sole Proprietorship. A single-member LLC is a State legal structure, not a Tax structure. You stated some liability issue was driving the LLC decision.

And, again, which of these two people works for the business? That's a big part of what you asked = how the work gets done and by whom.