I was wondering if all engine fan blades are really made out of titanium.
Many, but not all. Rolls-Royce has been working on carbon fibre fan blades for a long time, using the material as far back as 1968 on the RR. Conway. They planned to use carbon fibre (Hyfil) for the RB.211 too, but had to switch to titanium when they couldn't get the Hyfil blades to work reliably during bird ingestion tests.
The GE90 uses carbon fibre fan blades, with titanium leading edges.