Technically you can get away with only adding a snippet to functions.php
if you want that defines your main content wrapper:
https://woocommerce.com/document/woocommerce-theme-developer-handbook/
remove_action( 'woocommerce_before_main_content', 'woocommerce_output_content_wrapper', 10);
remove_action( 'woocommerce_after_main_content', 'woocommerce_output_content_wrapper_end', 10);
Then:
add_action('woocommerce_before_main_content', 'my_theme_wrapper_start', 10);
add_action('woocommerce_after_main_content', 'my_theme_wrapper_end', 10);
function my_theme_wrapper_start() {
echo '<section id="main">';
}
function my_theme_wrapper_end() {
echo '</section>';
}