The order IDs are out of order as WordPress saves everything as a post. For example, each pages are posts, media files are posts, products are posts, orders are posts, and posts are posts. Each post is assigned a post_id. All of these posts (media, pages, posts, etc) use the same database table and because of that they can't share the same post ID.
If you want to have consecutive order numbers then I would recommend the following plugins:
Using the free version will allow you to start your order numbers from your last highest order number. For example, if your last order number was #4861, using this plugin will start your next order at #4862.