The problem is that you are running a loop from secondary query in front-page.php and the loop from main in page-home.php. So, the post data in page-home.php won’t be the data from the WP_Query in front-page.php.
Additionally, you are trygin to get full template files as template parts, which is not correct. I mean, front-page.php is a full template will header, content and footer and page-fome.php is also a full template with header, content and footer. You should re-think the logic to split template parts.
A basic (and silly) example to show you a correct approach:
front-page.php:
<?php get_header(); ?>
<?php
$query = new WP_Query('pagename=home');
if ( $query->have_posts () ) : while ( $query->have_posts() ) : $query->the_post();
get_template_part("content");
endwhile; endif;
wp_reset_postdata();
?>
<?php get_footer(); ?>
page-home.php:
<?php
/*
Template Name: Home
*/
?>
<?php get_header(); ?>
<section id="first_section">
<img class="jumbo wow bounceInDown animated" data-wow-delay="2s" src="https://wordpress.stackexchange.com/questions/197061/<?php echo get_template_directory_uri(); ?>/images/jumbo-illustration.png" alt="Webdesigner and Developer" />
<div class="tagline-wrapper wow bounceInLeft animated" data-wow-delay="2.5s">
<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
get_template_part("content");
<?php endwhile; ?>
</div>
<?php else : ?>
<p><?php _e( 'Sorry, no posts matched your criteria.' ); ?></p>
<?php endif; ?>
</section>
<?php get_footer(); ?>
content.php:
<h3 class="tagline"><?php the_content(); ?></h3>