I thought for most of the time that I don't have routines either. But, similarly to
@Judge, my days start very similarly and I find it very uncomfortable and stressful if that's disturbed (e.g. because we have guests). It creates more stress for the entire day. I have different routines for different scenarios (work day, weekend, visit to my parents'). I can mostly deal with other people being there, but my body has a stress response. I am most relaxed when it's just me. I don't have these routines consciously, but I notice that I need them because it makes me feel bad if they're disturbed.
I believe most people have these morning routines, though? Maybe just the amount of peace it gives us varies.
I hate it for example when, just after waking up, my partner already wants to make plans for the day or discuss something. That's very stressful for me. I need my time in the morning, going through my ways. We can make plans after breakfast.
It's also stressful for me if we have an overnight guest, and I come across them before breakfast. I don't really want to talk yet then, but I do because it's polite. I need my morning non-socializing time to sort of boot. I am able to socialize, but it's uncomfortable and stressful.
I am a creature of habit in other things, though. I always walk the same ways. When on my own, I always buy the same groceries and cook the same selection of meals, up to the point that my partner worries a bit when he's away about me not getting all nutrients because my meals tend to be limited, rather bland, and repetitive. I always brush my teeth in the same pattern. Just some examples.
But if those routines and habits are disrupted, I can cope. I just don't like it.