looks like the later set of Singer attachments, so yes, like what would have come with the 201 and 15-91 (missing screwdrivers though) - PLUS you got the adjustable zipper foot.
A picture of your Davis warranty would be neat - Davis was out of business long before 1955, sure it's not 1925?
I believe the Manual is for a National made machine, it takes top clamping feet, so it appears you got three unrelated items, Davis Warranty, National manual and Singer attachments. I think you did very well with your thrift store find!