The problem of concluding that Isaiah is talking about Jesus is that Isaiah was already an ancient and significant religious text when the New Testament was written. One could reasonably conclude some of the events attributed to Jesus were written to fulfill previous prophesy.
Kind of the point of prophesy, is it not? To fulfill it? As a matter of fact, the New Testament authors sometimes said that Jesus took deliberate actions to fulfill the prophets.
Anyone can just wave his hands and say the writers of the New Testament were lying, but there are several historical texts and studies that disagree. This forum does not allow for the time to discuss the hundreds of prophesies fulfilled by Jesus - most out of anyone’s control, except for God.
If you haven’t made up your mind, you might want to read “The Case for Christ”. Pretty objective. I don’t want to persuade you. If I can talk you into it, someone else can talk you out of it. You need to find out for yourself.
God Bless.