I also faced the same issue sp.js and sp.runtime.js etc. were not loading with page load I tried different approaches finally with below code I am able to load them, might it help

I also faced the same issue sp.js and sp.runtime.js etc. were not loading with page load I tried different approaches finally with below code I am able to load them, might help

<script type="text/javascript" src="/_layouts/15/sp.runtime.js"></script>
<script type="text/javascript" src="/_layouts/15/sp.js"></script>
<script type="text/javascript" src="/_layouts/15/sp.core.js"></script>
<script type="text/javascript" src="/_layouts/15/1033/strings.js"></script>
<script type="text/javascript" src="/_layouts/15/clienttemplates.js"></script>
<script type="text/javascript" src="/_layouts/15/clientforms.js"></script>
<script type="text/javascript" src="/_layouts/15/clientpeoplepicker.js"></script>
<script type="text/javascript" src="/_layouts/15/autofill.js"></script>
<script type="text/javascript">
$(function() {
    getSPOffset();
    LoadData();
});

function initializePeoplePicker(peoplePickerElementId, allowMultipleValues, isPeopleOnly, GroupID, user) {
//debugger;
                        SP.SOD.executeFunc("clienttemplates.js", "SPClientTemplates", function() {
                            var schema = {};
                            if(isPeopleOnly) {
                                schema['PrincipalAccountType'] = 'User';
                            }
                            else {
                                schema['PrincipalAccountType'] = 'User,DL,SecGroup,SPGroup';
                            }
                            schema['SearchPrincipalSource'] = 15;
                            schema['ResolvePrincipalSource'] = 15;
                            schema['AllowMultipleValues'] = allowMultipleValues;
                            schema['MaximumEntitySuggestions'] = 50;
                            schema['Width'] = '280px';
                            if(GroupID != null) {
                                if (GroupID > 0) {  
                                    schema['SharePointGroupID'] = GroupID  
                                }
                            }
                            SPClientPeoplePicker_InitStandaloneControlWrapper(peoplePickerElementId, user, schema);
                        });
    
}