Originally Posted by
JoeTBM
Worn chain or bent link on chain
Worn or bent chain ring (on crank)
Misaligned chain line
Most probably the above. That chain looks horrible. And no, you don't seem to have a chainring that looks like the product image you posted above.
Check chain wear, chainring wear, cassette wear. You can't use extremely worn out drivetrain components and expect to not have problems.
And yes, that pulley jockey looks so extremely worn out. Although that won't be a factor in the chain falling off.
There are hundreds of videos on YouTube showing you how to check for drivetrain wear, and hundreds more websites. You should have a look at some of them.
Also, your drivetrain is extremely dirty, and the chain doesn't appear to have any lubrication at all.