Do standalone Oblivious Transfer (OT) Protocols exist?
The term "stand alone" in secure computation typically refers to the case of a protocol being run once, and not to assumptions. In any case, what I assume you are really asking is what assumptions are needed for OT. You are indeed correct that OT is built from asymmetric assumptions, and this is actually inherent for black-box constructions. This was studied in The Relationship Between Public Key Encryption and Oblivious Transfer.