For people arguing they have free will, they typically mean they have the ability to do other than what they did do. That is, whenever they make a choice, they do so under the belief that they could have, in principle, made a different choice. As far as science is concerned, such a free will does not exist, because the behaviors you exhibit appear to be completely explainable in terms of the environment impressing upon you, and the effects that impression has on your neural activity. There is no “you” making free decisions in this picture. There’s just stuff bumping into other stuff, and how is that free?
Regarding a general consensus of free will, that’s just not even an argument anyone should care about. Plenty of people are flatly told they have free will because, “they don’t have a choice, God made them with free will”. Others/most are simply uneducated or under-read on the subject. That’s fine, but it doesn’t mean their opinion should weigh on our conclusions. If you show most people an optical illusion and ask them if it appears to be moving, they’d say yes, even though science will tell you there’s nothing moving.
I personally am a hard deterministic regarding free will. I think we have a will but nothing about it is free. It is subject to natural laws just as a rock rolling down a cliff. That’s fine. There’s a related philosophical position of compatibilism, which believes that we have a determined will, but that the truth of the determination does not undercut our ability to talk as if and use the phrase free will as if we really do have such a thing. In this sense, compatibilists would say we don’t have the ability to do other than what we are determined to do, but since we might not yet know what we are determined to do, then that ignorance captures what is meant by free will. So compatibilists are determinists, they just think free will as a concept is compatible with that determinism.