Jesus Homo Salvatore? Jesus the man Saviour.
IHS= the first three initials of the Holy name
JESUS. They are greek letters: Iota, Eta, Sigma. The confusion is the capital letter Eta: it is "H" in its capital form, "e" in lower case.
If the holy name were abbreviated in lower case letters you would see "ies". There was(is) no "J" in Greek or Roman alphabets so "i" was what was used to get the sound we say in latin when the "i" is followed by the letter "e". This diphthong (ie) sounds like a "y"--Yesus. Hope I did not cause confusion.