Why do other religions exist if Yahweh is the one true God? God is omnipotent and loves his human children. If that is the case why does he allow the continued propagation and existence of other religions.
Does this signify that there is in fact no reason for God to mind the existence of other fictional Gods, which further implies that God actually doesn't care about us and that we are just created and left to our own devices?
The premise in the question :


  Does this signify that there is in fact no reason for God to mind the existence of other fictional Gods, which further implies that God actually doesn't care about us and that we are just created and left to our own devices?


. . is incorrect.

God has specifically stated :


  Thou shalt have no other gods before me [Exodus 20:2 Deuteronomoy 5:6 KJV]


This was addressed to the nation to which he chose to express the Law by the mediation of Moses. And the history of Israel contains many examples (the Assyrian and Babylonian captivities in particular) of God judging Israel when they followed other gods than himself.


  I the LORD thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me; [Exodus 20:5 KJV]


God does not 'allow the continued propagation and existence of other religions' as can be seen in history and as can be seen contemporaneously by the natural judgments that fall upon idolatrous nations.