Cover: unusually for this jam, you did not include your cover graphics in the PDF, even though you went to the trouble of creating an attractive cover image. It doesn’t seem that you are particularly short of space, why not dedicate at least part of the front page to your book title and image?
Some of the information on the itch.io page is missing from the PDF, like author names and “System agnostic Weird Fantasy dungeon crawl”, which seems like an important detail. Including this info in the PDF would make it more self-contained.
Layout: everything is clearly laid out. The page margins are generous, perhaps overly so (smaller page margins could be traded for including more title information/graphics). In contrast, the Enchantman pop-out box would benefit from some spacing/padding between the box outline and the text.
Art: The cartography is simple, clear and attractive. I like the interior art for the Enchantman. You could consider using the background tint for the entire “Enchantman” pop-out box, not just the illustration.
Adventure setup: As I understand, the characters are going about their business in a fantasy world until a spaceship lands, bringing them into contact with elements of sci-fi/Weird Science for the first time. The spaceship is the scout/vanguard for an invading empire. You provide a few good hooks to get the party involved.
The Enchantmen look like formidable opponents, immune to all magic and with powers of regeneration. One would be tough, 3-6 could be a TPK unless the party have plenty of high-level fighters. Even running away seems to be of limited help as they “won’t ever stop”. Maybe they should have some vulnerability so stopping them becomes a puzzle/solvable problem?
Would be nice to include some weird science technology “magic” items.