Why do so many people talk about the anti-Christ as if it he was one person in history. John the apostle defined “anti-Christ” as anybody who denies that Jesus is God in the flesh. (I John 4:2-3) That makes whole groups of people and even some religions “anti-Christ.” They were in the world then and they are in the world now!
You are correct in your interpretation of John’s “spirit of anti-Christ” and of the 40 or more titles given him in Scripture, “anti-Christ” is perhaps the least accurate. Technically he’s a “pseudo-Christ” because he pretends to be the Christ.
But regardless of that, there is a person who comes on the scene at the end of the age who personifies John’s spirit of anti-Christ. So many personal pronouns are used of him that it’s impossible to see him any other way. Daniel called him the little horn (Daniel 7:8) and the coming prince (Daniel 9:26), Paul called him the man of lawlessness (2 Thes. 2:3), and to John he’s the beast (Rev. 13:1), but the world thinks of him as the anti-Christ.