I don't think it matters what other groups think, it matters what the ICC thinks, and they already ruled they think Palestine is a state, at least in a preliminary fashion (i'm sure if this gets to trial the question will be relitigated).
Additionally ICC only has juridsiction if Palestine is a state. So the entire thing goes away if Palestine is not a state (since only states can aceede to the rome convention).
I do not think Palestine being a state is the same question as if this conflict is international. I think it may be possible for both Palestine to be a state and this conflict be non international. However IANAL and that is pure speculation.
Additionally ICC only has juridsiction if Palestine is a state. So the entire thing goes away if Palestine is not a state (since only states can aceede to the rome convention).
I do not think Palestine being a state is the same question as if this conflict is international. I think it may be possible for both Palestine to be a state and this conflict be non international. However IANAL and that is pure speculation.