Your problem is not that the image zooms too much. Essentially, your problem is that your image doesn't have enough width, so Shopify increases the image size to fill the width of the browser window.
You are encountering such a problem because you are using an image with a ratio different from the ratio recommended by Shopify. The recommended ratio for image banners by Shopify is 3:2. The best solution is to replace the current image with a new image with the appropriate ratio
If you still want to use the current image, you can try the following solution:
In Online store, select Themes -> Customize
In the Home page, select Image banner, in the banner height section, select Adapt to first image.