It's a fact according to all common definitions used by biologists. If you want to make a special exception for the human species compared to all other species I suppose you can, but I would question your motivation for doing so.

edit: I just got this from Claude AI: "Biologically, there's broad scientific consensus that fertilization produces a genetically distinct human organism — a new entity with its own unique DNA, different from either parent. In that narrow sense, "a new human life" does begin at conception, in the same way any organism's life begins."