It’s a lesson every writer must learn, something they need to embrace, and one which will save your sanity. Your first draft will never be perfect, so stop trying to make it so, just get through it, then go back and start revising (better to take a break first though).
If you need more evidence of that, take a look at Gene Roddenberry’s first ideas for Star Trek:
STAR TREK is a “Wagon Train” concept — built around characters who travel to worlds “similar” to our own, and meet the action-adventure-drama which become our stories. Their transportation is the cruiser “S.S. Yorktown,” performing a well-defined and long-range Exploration-Science-Security mission which helps create our format.
The year is “Somewhere in the future.” It could be 1995 or maybe even 2995 […] The “skipper” [is Robert M. April], almost thirty-four, Academy graduate, rank of captain. Clearly the leading man and central character. This role is designated for an actor of top repute and ability. A shorthand sketch of Robert April might be “A space-age Captain Horation [sic] Hornblower.”
Spock is described as looking satanic, which you could argue survives into the final version, but half-Martian and red. No. Roddenberry shows his penchant for middle initials, but Robert M. April doesn’t work nearly as well as James T. Kirk.
Need more evidence? Go look at the numerous drafts of Star Wars before we got to A New Hope.
The JediKane Starkiller and his two sons, Deak and Annikin Starkiller live on the Fourth Moon of Utapau. Their seclusion from the forces of the Galactic Empire is interrupted by the arrival of a Sith flying a Banta Fourstarfighter.
The Jedi and his sons go to investigate, but the Sith gets a jump on them, killing Deak with a single blow. Their foe is no match, however, for a Jedi Master, and Kane avenges his apprentice. It is clear that the exiles must flee the Kissel system and they leave for their homeworld of Aquilae…
Practically all the factions go through a series of name changes and the plot if vastly different, moving from a cheesy b-movie to what we know and love today.
So learn to love re-drafting, it really does help, and don’t put too much pressure on your first draft.