I don't know with 100% certainty, but I'm pretty sure that the air passes throught the blower motor before the filter. My reasoning for this is because when I have removed my blower motor assembly to lubricate the fan due to it squeaking, there was a bit of debris in the fan area. Stuff like little pieces of leaves. This debris was way too large to have passed through the cabin filter only to get stuck in the blower fan, so it must have come from the air inlet that feeds the system.

I can't remember from the last time I changed my cabin filter, but what side of the filter was clogged with debris when you removed it? If it was the side of the filter that is closer to the fan, as opposed to the side that is closer to your climate control unit on the centre stack, then that's the side that the air enters the system from.

If you want to clean out your blower motor, its an easy job. It takes around 20 minutes to remove and replace, and the only specialized tool you'll need are torx head bits for a couple of the screws. The access panel is just to the right of your cabin air filter.