So, you should regard 1 John 2:2 as a precious verse. It has great rhetorical power for presenting the freeness (distributive universality) of the Atonement. But the matter of who in particular Jesus' Atonement was designed to save is a different matter. It is, in fact, a deeper matter.
And when we look careful at the peculiar language conventions of the Greek text and the overall Biblical context (e.g., John 11:51-52) and the logical problems I identified in post #73, we discover that the Calvinistic position is correct.
Were the entire body of humankind to accept Christ, his sacrifice would be sufficient for all of them.