ACF: Only get first row of a Repeater Field

ACF has a function called get_row_index() that you can utilize. Here is how you can possibly use it in your case

    <?php
      $active="active";
      while ( have_rows('images') ) : the_row();
      $image = get_sub_field('image');
      if(get_row_index() == '1' ):
    ?>
      <img src="<?php echo get_template_directory_uri(); ?>/files/images/<? 
 php the_sub_field('image'); ?>" class="img-fluid is-slider-item" />
    break;
    <?php $active="";
    endwhile;
    ?>
    <?php endif; ?>

Notice I checked to see if the row index was 1 (the first row) then displayed what was needed within that logic.

Hope this helps!