For the life insurance benefit, is the "yield" essentially just 5%? Basically the other 100% is just returning the money to the owner's family right?

Are you referring to the 105% of account value as "yield"? The whole 105% is the death benefit that will be paid to your loved ones upon your demise:

Singlife Insurance Benefits

We don't think of death benefit as "yield". What is considered yield in the case of Singlife is the crediting rate, currently at 1% pa for the 1st $10K.