Vacuuming is an area of disagreement between manufacturers and professionals alike. My view is to vac it thoroughly with a good upright, using the correct technique, several times a week. Rule of thumb from carpet manufacturers is to always use a good quality upright machine except on wool loops and shags, when you should use a pure suction machine.
The shedding fibres will typically be surplus from manufacture or possibly a short staple fibre or a loose twist, or perhaps a poor set on the twist or even any combination of the above. Probably other reasons too.
If there is nothing wrong with the carpet, the shedding will reduce with time, but it is essential to vac well and regularly.
Safe and happy vaccing

The Ken