WP Custom user role with custom post type edit capability. Using this code we will be able to control a user to edit a post type only.

wp-custom-user-role-with-custom-post-edit-ability.php

/*
  Registering new Role
===============================================*/
function TallyFunctions_add_roles_on_plugin_activation() {
    add_role( 'shop_helper', 'Shop Helper', array( 'read' => true, 'level_1' => true ) );
}
register_activation_hook( __FILE__, 'TallyFunctions_add_roles_on_plugin_activation' );


/*
  Edit post type for added our new capabilities
===============================================*/
add_filter( 'register_post_type_args', 'TallyFunctions_change_capabilities_of_shop_helper' , 10, 2 );
function TallyFunctions_change_capabilities_of_shop_helper( $args, $post_type ){

	$custom_types = array('tallykit_doc', 'preview', 'tally_showcase', 'product');
  
	foreach ($custom_types as $custom_type){
		if ( $custom_type === $post_type ) {
			$args['capabilities'] = array(
				'edit_post' => 'edit_shophelper_post',
				'edit_posts' => 'edit_shophelper_posts',
				'edit_others_posts' => 'edit_other_shophelper_posts',
				'publish_posts' => 'publish_shophelper_posts',
				'read_post' => 'read_shophelper_post',
				'read_private_posts' => 'read_private_shophelper_posts',
				'delete_post' => 'delete_shophelper_post'
			);
		}
	}
	
	return $args;
}


/*
  Add the role capability 
===============================================*/
add_action('admin_init','rpt_add_role_caps',999);
function rpt_add_role_caps() {
    $role = get_role('shop_helper');               
    $role->add_cap( 'edit_shophelper_post');
    $role->add_cap( 'edit_shophelper_posts' );
    $role->add_cap( 'edit_other_shophelper_posts' );
    $role->add_cap( 'publish_shophelper_posts' );
    $role->add_cap( 'read_shophelper_post' );
    $role->add_cap( 'publish_course_documents' );
    $role->add_cap( 'read_private_shophelper_posts' );
    $role->add_cap( 'delete_shophelper_post' );
}

/*
  Allow this role to access wp-admin when using WooCommerce
===============================================*/
function tally_theme_enable_wp_admin_user(){
	if( is_user_logged_in() ){
		$tally_theme_enable_wp_admin_user = new WP_User(get_current_user_id());
		if($tally_theme_enable_wp_admin_user->roles[0] == "shop_helper"){
			add_filter( 'woocommerce_prevent_admin_access', '__return_false' );
			add_filter( 'woocommerce_disable_admin_bar', '__return_false' );
		}
	}
}
add_action('init', 'tally_theme_enable_wp_admin_user');