Others with better learning and understanding may answer differently, but from my limited knowledge, no.
The US forces went into action just as the German forces were nearing Paris and the allied armies were nearing collapse. US forces were used primarily to halt the German advance and then in the counter attacks that followed.
Our forces weren’t in static positions long enough to have developed such extensive systems of fortification.
Not quite . Ludendorff planned his spring 1918 offensive against the English and French before any great numbers of American troops could arrive . The attack succeeded but it ran out of steam when it's supply became over extended and Australian troops where sent in against it . There where Americans there but not in great numbers.
The English offensive stated on August the 8th , the day Ludendorff called the black day of the German army . American troops came in in much greater numbers toward the end of August and early September . In November the Kaiser fled , the German Republic was declared on Nov. 9th and the Armistice on the 11th.