The file number and the shutter count are not the same thing.

• IMG_3881.JPG does not reliably show total shutter actuations. File numbering can continue from prior settings or media history, so it isn’t a trustworthy way to judge whether the camera is used.
• The 256 count shown in the camera is more likely the meaningful number here. A small shutter count on a brand-new DSLR is commonly due to factory testing/inspection.
• If you want a more accurate shutter count, use a Canon-compatible shutter count utility rather than the filename.

Even if the camera had a few hundred or a few thousand test shots, that is still very low for a DSLR shutter and usually not a practical concern. Also note that some shutter count values can change or reset after service or firmware-related work.

So, based on the information here, the most likely explanation is normal factory testing, not significant prior use.