No. Human sacrifice, in the definition I have given, has a clearly defined purpose (which I didn't state, because I thought this was implicit): Winning favour with the god(s). That only works in any religion I know of if you declare the purpose of making a sacrifice before the gods in some way.
The Romans did this through the ritual of immolation, where the animal was marked as a sacrifice by spreading mola (wheat spelt) and salsa (salt) on it. No immolation, no sacrifice. If they killed someone without immolation, to them it didn't have the purpose of pleasing the gods and thus wasn't human sacrifice. Edit: "immolation" in this context might be somewhat different in the english meaning. See https://en.wikipedia.org/wiki/Mola_salsa for what I mean.
A lot of religions (don't know about the Roman in that aspect) also frown upon the intent of a sacrifice being impure: If you do the sacrifice with more than just the goal of pleasing God, e.g. to additionally get rid of that obnoxious goat/cock/person/..., then God won't be pleased.