So when someone makes an ordinal they are not using tapscript right?
They do. They wrap arbitrary data in a tapscript and inject it in the witness part of the transaction.
Does this mean that I could do an ordinal in a non-taproot address bitcoin transaction? So I could mint an ordinal with a P2PKH address?
An ordinal specifically? No, because the ordinal protocol relies on taproot, AFAIK. However, arbitrary data? Certainly. You could achieve that by treating multiple P2PKH as 20-byte blocks. I think you can achieve it with OP_RETURN too, but there are standardness limits.