Recently I noticed that Genesis 2:18 in the LXX uses plural and not singular like TM. Where the TM says "I will make....", the LXX says "let us make..."

Can someone tell me what version are true and why? Does the oldest LXX (so, before Christ) have the plural or the singular? Does the Qumran have the singular or the plural? If the older LXX has the plural, why did later scribes chose to add plural? There was no trinitarian influence at all.