Heard something walking on my roof last night and it wasn't an animal

Interesting one this. The key thing I'd want to know is the pattern of the footfalls - because animal movement tends to be either four-point contact (scrabbling, scratching) or in the case of birds you get that light rapid tapping. What you're describing sounds like it has a deliberate cadence to it, which is a different thing entirely.

I've looked into a few cases up here in Whitby where people reported similar and the ones that stuck with me were the ones where the witness mentioned a kind of weight to the sound, like the roof was actually flexing slightly under whatever it was. Tiles don't lie.

What was the weather doing? Any electrical interference beforehand, lights flickering, that sort of thing? I ask because some of the more credible MIB encounter reports - and I know that sounds like a leap - involve unusual sounds on or around the property in the hours before contact. Worth logging everything you can remember regardless.

What's the roof construction, pitched or flat?

@Phillsy makes a solid point about the footfall pattern. What I'd add is - did it have any rhythm to it? Human-like bipedal movement has a very distinct left-right cadence that's genuinely hard to mistake once you've heard it. I've done a fair bit of EVP work in old buildings and you get really attuned to the difference between random movement and deliberate, paced stepping.

Also worth asking - what's the roof material? Slate carries sound differently to tile and can exaggerate or distort the weight of whatever's up there. Cornwall has a lot of old slate roofs and I've had some weird experiences with sound travelling in unexpected ways on them.

But yeah if it was genuinely two-point bipedal contact thats the detail that matters most here. OP needs to give us more on that.