Excel writes UTF-8 files with a byte-order mark (EF BB BF) at the start. Shopify reads that as part of the first header name, so Handle becomes a column it does not recognise.
Use a tool that writes BOM-free UTF-8, or add a BOM-stripping step to your export.
The free Shopify CSV checker names the exact line for each of these problems. The paid Rescue Kit adds 20 more error cases, a template in Shopify's column order, and the checker as a script you can run in a pipeline.
See the Rescue Kit →