Using the term "neutral glue" I've honed my list down a bit from where it was last year. It's aso possible that my dressing is more formula-driven than it was a year ago! Images and examples at the end.

Essentials:

• Fitted knit tops in black and navy. In the winter this means turtlenecks and crewnecks, and in the summer it’s tees and sleeveless tops/tanks. They are HEWIs because I want them to fit close to the body without being body-con, and the fabric needs to be substantial and natural-fibre. The summer tops are easier because bare arms break up the expanse of solid colour, but the long-sleeve winter ones absolutely need some texture or detailing: rib knit, buttons (like a henley), tipping or piping, etc.
• Straight-leg mid-to-high-rise casual pants in black, blue and olive. I’m intentionally listing casual pants instead of jeans because, while I do need some denim, having some variety is equally important to me. I feel like good cord/canvas/chino pants are some of my biggest HEWIs because it’s difficult for me to get dressed without them (I’m a stodgy old prep at heart!). I do like to have a range of denim washes from very saturated to very faded, but no heavy distressing/rips/holes/patches.
• Chunky-yet-streamlined footwear in black and dark neutrals. Black is the footwear colour I use the most all year long, followed by burgundy and navy. I’m leaving this somewhat open-ended as I’m thinking about adding some chocolate brown footwear in the next year. There are very specific aesthetic/design/comfort elements I look for in a shoe and the best way I can think to describe that is “chunky-yet-streamlined” but I’m not sure if that makes sense to anyone else. Does it need to, though?
• Loose linen bottoms in blue, olive, and black/grey (I don't love black linen but have ended up with some of it anyway; I think I'd like to swap it out for something lighter). My preferred alternative to jeans for hot/humid weather (¼ to ⅓ of the year for me). Silhouette ranges from mid-thigh shorts to midi skirts to full-length pants.
• Navy puffers. I have a long one and a short one, worn day in day out. My black and olive wool coats receive an equal number of wears; is “longish wool coats” a separate essentials category? I have two and have a perceived need/desire for a third, which would probably end up being a statement color and/or silhouette. I also would not say no to statement puffers...

Maybes:

• Casual patterned dresses. I have a handful of FFBO summer dresses, striped or polka-dotted, that I would have a hard time doing without. The fact that they are patterned, not blocks of solid colour, means they offer enough visual interest without accessories/toppers/etc. That makes them super useful on very hot summer days. But are they statements rather than essentials?
• Breton tops. I have three, all different colour combos. I feel no need to duplicate colour -- that would split wears. I also feel no need for a classic navy/white breton. Am I wearing these as statements? One is oversized, one is cropped and boxy, one is red. They tend to be spring/fall items for me, for days when I know it will be too warm for a topper by the afternoon so I want my first layer to have some visual interest.
• Menswear-inspired shirts with low-contrast pattern. I have two pinstriped oxfords, two printed chambray shirts (blue on blue), and about half a dozen muted plaid shirts (black watch, navy/burgundy, etc) in various weights and sleeve lengths. Year-round it would be hard for me to get dressed without these. Some can be worn on their own, while others are good layered, either open or buttoned-up.

The Small Epiphany:

I would have considered all three "Maybes" essentials as recently as a year ago. The wrench in the gears is that I have added quite a handful of patterned trousers (plaid, leopard, polka dot) which necessitate solid-colour tops. I just didn’t have many, or any reason to reach for them, before the introduction of patterned pants.

I used to spend almost everyday wearing some variation on solid bottom/patterned (or graphic) top. Now I sometimes invert that, usually in the winter: bottoms are visible underneath a coat, so the addition of pattern on the bottom is a solution to winter boredom. If I wear black or dark blue pants underneath my black or dark blue knee-length coats, I feel like a big monochrome blob. Having patterned pants, even if the pattern is subtle and neutral, breaks up the visual monotony in a more effective way than a patterned top does. This also explains my love of patterned and textured tights and hose, and why I don't reach for my opaque black or navy ones very much.

Patterned pants still feel more statement-y to me than patterned tops, but am I wearing my striped and plaid tops as statements on days when I want to do without a topper? Maybe I am.