You've raised some issues that would take us way off topic and probably into a few years' discussion if we pursued them so I just want to stick to the point about "how we think of each other" which to you seems to be out of the usual realm of thought for a "true Christian."
Not sure why. I'm commanded to love my neighbor as myself. That command is a summation of the second part of the Ten Commandments. Not to murder them, which Jesus extended to hating them, not to bear false witness against them, not to commit adultery which is usually an offense against another, not to covet anything that belongs to them, not to steal from them. Pretty basic stuff but it has extended applications that can take a few sermons to fully describe each offense. Stealing for instance includes stealing their reputation, their standing in others' eyes. Your attack on "true Christians" is a violation of this command I'd say, but then we are all guilty of putting each other down, aren't we. There's a general indictment of gossip in here too, clearly overlapping with not bearing false witness, or creating a negative view of a person. I suppose I'd refer to these commands as an argument for treating all human beings as valuable, including in how we deal with them in death.
Those commands are just one Biblical basis for honoring other human beings and it's specific to individuals but does imply a general respect as well.
Another is that we are told we are all made in the image of God. And this was reinforced when God told Noah that whoever sheds man's blood, by man shall his blood be shed.
And David asks God, What is man that You are mindful of him, or take knowledge of him? And Job asks What is man that You should magnify him and set Your heart on him? God regards us highly, though why He does can be mysterious.
All these are Biblical reasons to value, honor, respect and seek the wellbeing of humanity, but as I said I felt the same before I became a Christian and hated the kind of stuff that treats us as accidental combinations of chemicals that are casually disposable, or as mere animals or less than animals. Not that I don't love animals too, but you get my point.
Now that I've said all that I've forgotten the context.