Cows arrive at the slaughterhouse in trucks but I think even the most cleverest of cows would struggle to build or drive a truck? I find your logic to be both flawed and childlike.
Properly read, the Bible is the most potent force for atheism ever conceived.
-Isaac Asimov

It wasn't a spaceship, that was pretty obvious.

Just after watching it and I think it was a meteorite as well. It could have easily broken off a comet at some stage which contained water/ice and had some form of organism in it. Either way it wouldn't be the first time a story for a sci-fi or horror film has come about from this.
Also there is no indication that the aliens are or should be more intelligent than humans. If anything it's suggested they're just following base animal instincts. As was stated earlier when they're all trapped upstairs in the pub and the creature is banging the sheep off the door, someone suggests it's like cats who leave birds/mice at doorsteps as gifts. Which then leads to another character saying it could be a mating ritual bringing a gift to it's mate which it thinks is in the pub because the main character was covered in fluids it's mate gave off when it attacked him.
I'd have to watch the start again, but I suspect the person who was sprayed by the female when it was in the lobster cage was also the person who was supposedly lured out. At least that's the impression I get from the film that they are just acting on base instincts. Either way it's a fun enough film.

A flaming meteor carrying a water-dependant tentacle monster riiiight. Anyway, I really didn't catch the part about the sheep. As a non-English speaker I got about 90% and that part must have been particularly mumbly
Ok, I could probably find some more plotholes but then again, I was too entertained most of the time to want to look for them. It's just that nagging feeling that a movie I liked could have been even better.
And of course, Ruth Bradley is the cutest thing. At first I thought I must have seen her in a Dr. Who episode - she would fit perfectly there - but then I realized it was her scene-stealing performance in Primeval where I remembered her from. Got a bit side-tracked now

If you'd been paying more attention, you'd've heard a character describe how the Grabber was dangling a dead sheep in front of their door, and another saying something like 'my cat does that'. Other discussions about the creatures following the smell of the female. These are alien creatures - who knows what their plans, instincts are? Are they intelligent? The story is deliberately unclear. As for a 'friggin' space ship' - I didn't see any space ship. I saw a flaming meteor, carrying who knows? Genetic material? Eggs? Some means for the creation of a creature that is adapted for the planet the 'spore' has landed on (in this case, deep ocean, coastlines). I think the writer is smarter than you give him credit for!