Your question seems to be framed from a christian/abrahamic perspective, and is about God's omni-benevolence property. Unfortunately, I've yet to find a sufficiently simple/satisfactory explanation for that question.
In some flavors, the view is that there is no omni-benevolence (think in the tradition of Roman gods, for example), other views include the position that God is not an entity per se and that the notion of conflicts and the pursuit of what is "good" are inherent to our human condition (think Buddhism). If you're inclined to hear abrahamic leaning interpretations, the most closely aligned I've seen is the idea of "God draws straight lines w/ crooked sticks" (i.e. things we perceive as injustices are actually not, but we cannot comprehend the greater good because we are imperfect, biased things). See also karma and beliefs of reincarnation.
As for the origin of entropy, there's a lot of different takes, some rooted in philosophical thought (e.g. Spinoza-like takes that everything is deterministic and RNG is an illusion), some more spiritualistic (e.g. the panentheist idea that the universe is contained in God and that there may or may not be a non-deterministic force underlying it all)
Personally, I don't try to obtain explanations for every claim of every denomination (trying to nitpick apart the exact definition of God as per christianity, for example), since at some level one needs to acknowledge the metaphorical/allegorical aspects of various religious texts. I find it more interesting to take note of what concepts/interpretations appear in multiple denominations, there's a surprising amount of overlap when looking at individual concepts separately from lore.
Aside from all the stuff about deities, there's also quite a bit of literature on the morals side. I find those topics to be have a lot more overlap among religions, with self improvement usually being a central theme.
Anyways, if these kinds of debates interest you, I would recommend looking into pantheism and derivations. A lot of common questions have already been contemplated by various schools of thought. The wikipedia article might be a good place to start.