Use OpenShot online video editor:
It's free and open source software that runs in your web browser.
You can import your script, record a voiceover, add images/stock footage, and edit together a basic video.
Export the final video and upload to YouTube.
Use Kapwing's online editor:
Kapwing provides a browser-based video creation and editing tool.
You can add voiceover audio, stock footage, images, text overlays based on your script.
Includes options to trim, resize, crop, adjust speed, add transitions, etc.
Export and upload the final video to YouTube for free.
Create a slideshow style video:
Use a tool like Canva to make simple title slides and image slides for each part of your script.
Record your script voiceover separately with free software like Audacity.
Combine the slides and audio in an online video editor like WeVideo.
Export and upload to YouTube when done.
The advantage of these options is you can create and edit a video fully in your browser without needing video editing software installed on your own computer. Good way to quickly turn a script into a video for YouTube without cost.