(Photo below). Is this safe?
Just a homeowner who has changed his fair share of fixtures and outlets... but have never come across this.
Two whites leading to the fixture white.
A red wire leading to the fixture black
And two black wires in the back that I don’t know where they’re going?
And bare wire (assuming neutral) just coiled up in there.
And there is burning/charring around the electrical box and inside the old fixture.
Is this configuration safe?
The closeup of the red wire linked in the comment does not appear particularly burnt to me (it'd be a quite strange spot to have a burnt spot, anyway).
What this setup appears to be is a new-style switch loop that provides neutral at the switch box, which is now required by the NEC (so that fancy dimmers/smart-switches/timers/... don't have to pull dumb stunts to power themselves). The black wires that are nutted in the back of the box are the always-hots (incoming from the power source and outgoing to the switch), the red wire is the switched-hot coming back from the wall switch), and the white wires are all neutrals (incoming neutral from the power source and neutral off to the wall switch location).
One thing I would check while you have this box open though is to make sure the grounds are made-up properly; the installer may have simply twisted the wires together without using a nut, which doesn't guarantee a proper connection. I would take all those bare ground wires, untwist them, add a ground pigtail to a 10-32 self-tapper (Garvin GSST or equivalent) driven into exposed metal on the fixture (this takes care of grounding the fixture), insert them into the correct size wirenut, and twist the wirenut on, so that you have them properly connected from here on out.
Is this lamp junk? If so, cut the wires right here
Strip those wires, get some orange wire-nuts, and splice the new lamp's black/white to the like colors. And you're done.
Pay no attention to the man behind the curtain.
The simplest explanation is those wires "don't belong to you", or to be more precise, don't belong to the scope of your project. They have other, unrelated but important jobs to do, whatever they may be -- I suspect in this case, they carry power onward from this box to serve other loads in your house. Messing with them will break that, but fortunately you don't need to.
Now in the last few weeks, we've had literally a question a day of "I'm changing a lamp or fan and there are all these other wires up there and I want to know about them / I am worried about them / I want to play with them / I took them apart and HALP". Yes, we really do get the latter, one memorable one really went sideways on him.
The difficulty in giving an answer is they're all different, and a lot of things are just un-knowable without a lot of popping covers off and testing - obviously one of your cables goes to the switch, but I can't guess where the other one goes.
And often the motivation is to learn about electricity, which is awesome. But even at best, trying to learn via chance-encountered bits and spurts of knowledge (e.g."Google learning") is a dreadfully time-inefficient way to learn, and gives swiss-cheese knowledge - essential things never get mentioned. The right way to approach this is to curl up for a few evenings with a "how to wire houses" book from the library, and then blend in a fair bit of searching here to add color. And then you'll look at that and go "Oh, yeah."
