(Exodus 15:1) "to the L–rd": They sang it to the L–rd, and not to flesh and blood as (they did) in (I Samuel 18:6) "And all the (rejoicing) women went out, etc." But here, they sang it to the L–rd, and not to flesh and blood.
When the Torah Records Then Moses and the Children of Israel Sang
Mekhilta Tractate Shirah 1:11