@OSO-Bear Judging by the output of the program and your makefile, it looks like your program was compiled for x86 (your computer). You'll have to use an xCompile.sh script like the example to cross compile your C program.
PS it's three backticks to open a code block, and three to close it. See this link for more markdown syntax.
IMO, it is nothing to worry about, when you updated the firmware you ssh keys changed and since old ssh keys get stored on your host machine under ~/.ssh/known_hosts, it sees a conflict and gave this warning. You can rectify this by deleting old keys, open file ~/.ssh/known_hosts with a suitable editor like vim or nano and delete the line containing old keys and try ssh again.
I did a factory reset to the Omega.
I went back to the documentation and followed all the steps from the beginning.
I came to the blink program called 'STK01-blink'.
I saved 'STK01-blink' to my Omega. I went to the terminal ran the code and IT WORKS!!!!
[ 4.489247] usbcore: registered new interface driver usb-storage
[ 4.499070] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[ 4.516900] init: - preinit -
[ 5.069174] usb 2-1: new full-speed USB device number 2 using ohci-platform
[ 5.367204] rt3050-esw 10110000.esw: link changed 0x00
Press the [f] key and hit [enter] to enter failsafe mode
Press the , ,  or  key and hit [enter] to select the debug[ 5.569477] random: procd: uninitialized urandom read (4 bytes read, 10 bits of entropy available)
[ 7.998915] jffs2: notice: (401) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
[ 8.023692] mount_root: switching to jffs2 overlay
[ 8.062463] urandom-seed: Seeding with /etc/urandom.seed
Error relocating /lib/libubus.so: uloop_cancelling: symbol not found
[ 8.202992] watchdog watchdog0: watchdog did not stop!
[ 8.208847] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00007f00
[ 8.219687] Rebooting in 1 seconds..
@ice-master your command line is wrong, this,
mount /dev/<device name> /mnt/ ; tar -C /overlay -cvf - . | tar -C /mnt/ -xf - ; umount /mnt/
notice forward slash on each side of mnt.../mnt/ you missed it three times.