My mama would rock me in the cradle [duplicate]

In the lyrics of the song Cotton Fields by Creedence Clearwater Revival there is the following sentence:

When I was a little bitty baby
my mama would rock me in the cradle

I feel like I understand the meaning, but I can't find out why is would used in such way.

What is the difference to the following:

When I was a little bitty baby
my mama rocked me in the cradle

The use of would here is an example of the habitual past tense.

The habitual past tense can be expressed using various constructions. These include:

• Auxiliary "used to" + infinitive
• Auxiliary "would" + infinitive
• Simple past tense

The "would" form is often used with dynamic verbs (such as "to rock") and especially when the subject is 3rd person.

Source: https://www.thoughtco.com/habitual-past-grammar-1690829