Seat belts are okay in certain circumstances. But how much experience do you have lifting with serpentine belts? Sounds like none.

I have seen engines lifted with them for years and years. As long as the belts are in good shape, it's all good. We have also used them to pull stuck mowers and many other things. When we have overloaded them pulling something more than we should have with them, we are always surprised just how much they would pull before failure.

For a serpentine belt in good shape, lifting an engine is no problem. Done it and seen it done dozens and dozens of times.

If you have reservations with them, don't use them. But real world experience with them does count for something.