Can I soul trap all creatures regardless of their level?

Solution 1:

No, not all creatures can be trapped using Soul Trap. For example Dragon's will always resist being soul trapped. The dragon souls will instead be absorbed by you directly.

Dwarven creations (Centurion's Sphere's etc.) are driven by souls captured in soul gems, so they don't have a soul themselves. So you can't re-trap these souls, instead the creations will drop filled soul gems themselves.

For other creatures there is no level restriction.

Source: Skyrim wiki souls talk page

Solution 2:

Also, some souls are protected by Arkay the god of death from soul trapping. Meaning, anything that isn't qualified as a monster by the game engine which is a little arbitrary. Vampires are protected if I'm not mistaken but Falmer aren't for example. For those you need a Black Soul Gem to capture them.

Solution 3:

Yes you can soul trap any creatures, but make sure to have a soul gem big enough to hold that soul.