I am part owner of an aircraft which was rebuilt using parts from 2 wrecks, (1960 and 1964 models), 20+ years before we bought it. After 17 years, we had to strip the fabric. The wing mainspar had been broken, but properly repaired. Only unrelated woodwork required attention.
I am part owner of another aircraft, which had been deregistered in the UK and moved to France. After being neglected, it was brought back to the UK, refurbished, and given its previous UK registration. That was about 20 years before we bought it.
The engine and airframe are separate, with their own logbooks. The airframe could be wrecked with no engine damage. Eg. Blown over with engine not running.
The engine could be damaged with no airframe damage. It could be rebuilt to new specifications, or replaced with a manufacturer's zero-houred engine.
Many aircraft have had several engines in their lifetime.