Chabad.org — English translation + Rashi
Torah Temimah points to Toras Kohanim (Sifra), on 3:1 (why called shelamim).
Sefaria — Sifra / Toras Kohanim
English: Why is it called shelamim? Because all have peace in them: the blood and emurim to the altar, the breast and thigh to the kohanim, the hide and meat to the owners.
Etymology of shelamim — the offering creates peace by sharing among altar, kohanim, and owner.
Shelamim share the animal among altar, kohanim, and owner. The name reflects that blood and sacrificial portions go to the altar, breast and thigh to the kohanim, and hide and meat to the owners, so that all parties have a share of peace in the offering.