I think you'll find that the majority of the British isles, including some of what is now Scotland, was populated by one of two peoples - pre Celts (Picts traditionally being named as one of those peoples) and P-Celtic speakers. The P-Celtic languages are the forefathers of Welsh, Breton and Cornish. Gaelic is not directly related to these languages[1], and indeed the Gaelic speakers in Scotland mostly migrated from Ireland - Scottish and Irish Gaelic being extremely closely related. Your list of "loan words" is therefore pretty late in acquisition. You can probably list the amount of actual P-Celtic loan words in regular use on 10 fingers. There's a massive body of evidence that the P-Celtic languages took a while to die out. A Celtic language was spoken in Cumbria (Cumbria itself coming from the same Celtic root word as Cymru, the Welsh name for the country "Wales"), and the traditional Shepherd counting systems[2] based on the P-Celtic counting system are still used even today to a certain extent.
[1] https://en.wikipedia.org/wiki/Celtic_languages [2] https://en.wikipedia.org/wiki/Yan_tan_tethera