Review notes:

• Template parts such as header, footer are not rendered because of the additional theme attribute.
  <!-- wp:template-part {"slug":"secondary-header","theme":"jaida"} /-->
  I tried creating a blank theme using CBT and exported. It has no such attribute. Created Theme created using plugin doesn't render template parts WordPress/create-block-theme#396 to investigate further.
  Fixed by removing the attribute here: b47f723

• queryId is found in the templates. It should be removed when the theme is exported.
  <!-- wp:query {"queryId":14,"query": {...} -->
  Created: Remove QueryId from the exported themes WordPress/create-block-theme#397
  Fixed by removing the attribute here: cc06710

• A 404 pattern existed, but it is not used in 404 template. This can be resolved by saving the block as pattern.
  And this 404 pattern should have not created by CBT. @beafialho Did you use a block theme (not a blank theme) as base while creating this theme?
  This also the case for footer, and comments patterns. They are not used.
  Related commits: f5df793 04556d3 23e782d

• Index and Archive pages has their own query definitions instead of a pattern. It's nothing wrong to have them this way. Moving them to a pattern is just an improvement. Leaving it as is.

• Minor issue: empty height is set for spacer block. This could be a fix for gutenberg itself. 1f821ea

• the assets such as images, screenshot can be compressed while exporting theme.

• optionally, check if the assets used in theme and include only those in the exported theme.