Thank you.
All considered, Pi-hole's installer is correct in pulling ARMv5 binaries in your case, even if your actual CPU is ARMv6 (because it is lacking hard-float support).
"Corruption detected" was likely prompted by your self-compiled pihole-FTL binary.
Your self-compiled binary may still be more specific for your cpu, but it would prompt for update failures.
If running Pi-hole's ARMv5 binary is working for you, you should consider using that to allow for smooth updates in the future.
That would leave lighttpd as the remaining cause of failure.
Could you please provide output as requested by Dan?