Fr dear Fr: Do be so kind as to excuse this Quaestio on an issue of liturgical minutiae, but is there a reason for the Kyrie at the beginning of Holy Mass?

Yes, inserted by the early popes at this point of the temple mass so as to affirm the Divinity of Christ, at a time when gnostics and Judaizers were subtly undermining his divine nature, hence the formulae, Kyrie, Christe, Kyrie. And it also is accompanied by the way with an absolution too, for venial and serious sins but not for grave and mortal sins, since these latter require the confessional, especially if they are accompanied by a fundamental denial of God like a fundamental option away from his grace.