Paul (Paulus) is a Roman name. Sha’ul is Hebrew as evidenced in Acts 26:14 where Messiah called him by his Hebrew name. There’s no evidence in scripture as to why, when, or by whom this change was made. The ancient Romans had a national hero named Paulus and perhaps his name was changed in order to appease the Roman people. It is also possible that Paulus was used to represent the Hebrew name Pallu (Genesis 46:9; Exodus 6:14; Numbers 26:5, 8) which means “separated” in reference to his being especially set-apart.
What about the name “Jesus?” (read on and you decide) Yahushua cannot be translated or even transliterated into English and “Jesus” cannot be translated into Hebrew. “Iesous” (a Greek name and a pagan one at that) is rendered as Jesus (no “J” in Hebrew language) in English versions.
In the “Greek-English Lexicon” of Liddell and Scott, under “Iaso”: the Greek goddess of healing reveals that the name “Iaso” is “Ieso” in the Ionic Greek dialect, “Iesous” being the contracted genitive form. David Kravitz, in his “Dictionary of Greek and Roman Mythology”, a similar form, “Iasus” is found being four different Greek deities. “Ies” is the abbreviated form of “Iesous.” Dr. Bullinger, in “The Apocalypse”, page 396 states that “Ies” was part of the name of Bacchus the Roman god of wine and intoxication and equated with the Greek god Dionysus. “If the origin of words are pagan, they and their meanings are still pagan, just hidden from us.”