On your Android smartphone: Mint web browser used to let you download pics and videos. Now they only allow you download videos. On your laptop: Go to the URL of the IG pic you wish to save to your PC. Click on the three-dotted menu and select “Go to post.” Right-click it and choose “View Page Source.” Do a 'Control Find' search by using the hotkey “Ctrl + F” then type .jpg in the search box. Find the first link, including the .jpg suffix, and copy it. Paste the URL into the address bar of a new web page. There you have it. Now you can right-click the photo and choose “Save Image As….” whatever equivalent is on your browser.
Seek & You Shall Find