Need to include a node field image in the page.html.twig template with Drupal 8? This is the most straightforward way I've found to do so. (This is using the file entity module.)

fragment-of-page-html.html.twig

              {% if node.field_hero_image.entity %}
                <img src="{{ file_url(node.field_hero_image.entity.uri.value) }}"
                     alt="{{ node.field_hero_image.alt  }}"
                     {% if node.field_hero_image.title %}
                       title="{{ node.field_hero_image.title }}"
                     {% endif %}
                />
                {% endif %}

Excellent!! Thx u!